Geothermal Heat PumpsClosed Loop Water-to-Water
Tetco TWV060 Geothermal Heat Pump Manual
Setup, everyday use, maintenance and troubleshooting for the closed-loop water-to-water geothermal heat pump, with verified specifications.
- ConfigurationClosed Loop Water-to-Water
- Heating COP3.5
- Cooling EER21.9
- Heat cost per million Btu$14.23
About the Tetco TWV060
The Tetco TWV060 is a closed-loop water-to-water geothermal heat pump from the ES6V line. This page covers its ENERGY STAR certified closed-loop (ground-loop) rating.
In this configuration it is rated at a heating COP of 3.5 and a cooling EER of 21.9. A COP of 3.5 means it delivers about 3.5 units of heat for every unit of electricity it uses. An EER of 21.9 means it removes 21.9 Btu of heat per watt-hour in cooling. Closed-loop ratings are measured with 77 °F (25 °C) fluid entering the heat pump in cooling and 32 °F (0 °C) in heating, simulating a buried loop near the end of each season.
As a water-to-water unit it heats (and, where the system is designed for it, chills) water for radiant floors, fan coils, low-temperature radiators or a buffer tank rather than blowing air directly. Among peers, its COP is higher than 92% of the 40 Closed Loop Water-to-Water models in our database and its EER beats 95% of them.
It is also recognized as ENERGY STAR Most Efficient, the program's designation for the top-performing certified products in a category.
Specifications
| Brand | Tetco |
|---|---|
| Model number | TWV060 |
| Model name / series | ES6V |
| Configuration | Closed Loop Water-to-Water |
| Product series | ES6V |
| EER (cooling efficiency) | 21.9 Btu/Wh |
| COP (heating efficiency) | 3.5 |
| Refrigerant | R-410A |
| ENERGY STAR Most Efficient | Yes |
Certified ratings by application
1 certified rating configuration is listed for the Tetco TWV060, sorted by COP. Ratings depend on the application, so compare the row that matches your installation.
| Application | EER | COP | Certified |
|---|---|---|---|
| Closed Loop Water-to-Water | 21.9 | 3.5 | August 2023 |
Safety information
- Installation, refrigerant work and electrical connections must be done by a licensed HVAC contractor experienced with geothermal systems, following the manufacturer's instructions and local codes. Most jurisdictions require permits for the heat pump and for drilling or trenching.
- Geothermal heat pumps typically run on a 208/230 V circuit. Switch off the disconnect and the breaker before opening any access panel; capacitors can hold a dangerous charge after power is removed.
- Call 811 (or your local utility-locate service) before any digging so buried gas, electric and water lines are marked.
- Do not operate the unit with access panels or the blower door removed.
- Closed loops are filled with water and antifreeze. Some antifreeze types (such as methanol or ethanol blends) are toxic or flammable; handle loop fluid only as directed by the installer and never drain it onto the ground or into a storm sewer.
- If your home also has a fuel-burning furnace, boiler or water heater, keep carbon monoxide alarms on every level and near sleeping areas.
Installation and first-time setup
A geothermal system is only as good as its ground connection. The ratings for the Tetco TWV060 assume correct source-side flow and temperatures, so the loop or well design deserves as much attention as the heat pump itself.
- Room-by-room load calculation
Insist on an ACCA Manual J heat-loss and heat-gain calculation. Geothermal equipment and loops are expensive to oversize, and an undersized loop drives entering-water temperatures down in winter, reducing capacity and efficiency.
- Ground-loop design
The loop length depends on the heating and cooling loads, soil or rock thermal properties and the loop layout (vertical boreholes, horizontal trenches or a pond loop). Ask for the loop-design calculation, and for large vertical fields consider a thermal conductivity test. Reputable installers follow IGSHPA design and installation standards.
- Flush, purge and pressure-test
The loop must be flushed at high velocity to remove air and debris, pressure-tested, and filled with the antifreeze concentration your climate requires. Ask for the freeze-protection temperature in writing.
- Hydronic distribution
Design the heating side for the lowest practical supply-water temperature — radiant floors and oversized low-temperature emitters let the heat pump run far more efficiently than high-temperature baseboard. Most installations use a buffer tank to prevent short-cycling, plus an expansion tank, air separator and mixing or limit controls where required.
- Verify water flow
Source-side flow must match the manufacturer's table — closed loops commonly run about 2.5–3 gpm per ton, while open loops often use less. Ask the installer to record flow and the temperature difference across the heat exchanger.
- Commissioning
Ask for a start-up report that records entering and leaving source temperatures, refrigerant pressures, airflow or load-side flow, thermostat and auxiliary-heat settings, and the loop fluid freeze point where applicable.
Using your geothermal heat pump
Thermostat settings
Choose a comfortable setpoint and leave it. Geothermal heat pumps work best holding a steady temperature; large setbacks in heating mode can bring on auxiliary electric heat during recovery, which costs several times more per hour than the compressor. If you use setbacks, keep them to a few degrees or use a thermostat with heat-pump adaptive recovery.
Auxiliary and emergency heat
Hydronic geothermal systems are often paired with a backup boiler or an electric element in the buffer tank. The controls should call for backup heat only when the heat pump cannot keep up; if the backup runs often in mild weather, ask your installer to review the staging settings.
Supply-water temperature
Efficiency falls as the heating supply temperature rises. Use the lowest setting (or the outdoor-reset curve) that keeps the house comfortable, and avoid raising the setpoint to "speed up" warm-up — radiant systems respond slowly by design.
If the system also provides chilled water for cooling, the controls must keep surface and pipe temperatures above the indoor dew point to prevent condensation on radiant floors and uninsulated piping.
Domestic hot water
Many geothermal units can be fitted with a desuperheater that preheats domestic hot water using waste heat from the compressor. If your installation has one, its circulator runs only when the compressor runs, and the water heater still provides final heating — check with your installer whether it was included.
Care and maintenance
Ground loops have no outdoor coil to clean and are largely maintenance-free, but the indoor unit and the source-side fluid still need periodic attention.
| When | What to do |
|---|---|
| Every 3 months | Check system pressure on the hydronic side and listen for air in the piping; bleed air as the installer showed you. |
| Every season | Check that the condensate drain and trap are clear (water-to-air units remove moisture in cooling mode) and that nothing is stored against the unit's access panels. |
| Every year | Professional service: check loop pressure and flow, verify antifreeze concentration and freeze protection, record entering and leaving water temperatures, and inspect electrical connections and the compressor. |
| Every year | Check the expansion tank pre-charge, buffer-tank temperatures, circulator operation and any mixing valves on the load side. |
| Every 3–5 years | Have the indoor coil and blower (or load-side heat exchanger) inspected and cleaned if airflow or temperature split has dropped. |
Troubleshooting
Geothermal heat pumps protect themselves with pressure and temperature switches, so most "no heat" calls trace back to airflow, water flow or thermostat settings. Work through the checks below before calling a technician.
| Problem | Possible cause | What to try |
|---|---|---|
| No heating or cooling | Thermostat in wrong mode; tripped breaker; disconnect off; unit in safety lockout. | Check mode and setpoint; reset the breaker once. Many units clear a lockout when power is cycled off and on — if it locks out again, call for service. |
| Unit locks out in heating mode | Low source-side flow; entering water too cold; low antifreeze concentration; dirty air filter. | Replace the filter and confirm loop or well pumps run. Repeated low-temperature lockouts point to a flow, antifreeze or loop-sizing problem for a technician. |
| Unit locks out in cooling mode | High head pressure from low water flow, a scaled heat exchanger or poor airflow. | Check the filter and blower; have a technician verify flow and the temperature rise across the heat exchanger. |
| High electric bills in winter | Auxiliary heat running too often; deep thermostat setbacks; loop delivering cold water. | Reduce setbacks and ask your contractor to review auxiliary-heat staging and entering-water temperatures. |
| Air from vents feels lukewarm | Normal heat-pump supply temperature (around 90–105 °F). | Judge comfort by whether the house reaches setpoint, not by the feel of the air. |
| Gurgling or rushing water sounds | Air trapped in the loop or hydronic piping. | A technician should purge the air; persistent air may mean a slow leak. |
| Water near the unit | Clogged condensate drain or trap; leaking fitting. | Turn the unit off, clear the drain and check fittings; call for service if water continues. |
| Some zones not heating | Air in the zone; zone valve or circulator not opening; supply temperature set too low. | Bleed air, check the zone thermostat, and have the controls and circulators tested. |
Energy use and running costs
At its rated COP of 3.5, the Tetco TWV060 uses about 84 kWh of electricity per million Btu of heat delivered — roughly $14.23 at $0.17 per kWh.
| Heat source | Energy used | Estimated cost |
|---|---|---|
| This heat pump (COP 3.5) | 4,187 kWh | $712 |
| Electric resistance heat (COP 1.0) | 14,654 kWh | $2,491 |
| 95% AFUE gas furnace | 526 therms | $789 |
| 80% AFUE gas furnace | 625 therms | $938 |
For cooling, an EER of 21.9 means each ton of capacity (12,000 Btu/h) draws about 0.55 kW at the rating point. Over 1,000 full-load cooling hours a year — an assumption typical of a mixed U.S. climate — that is about 548 kWh per ton, or $93.15 per ton at $0.17 per kWh. Multiply by your system's tonnage for a seasonal estimate.
These figures are based on the certified rating point. Real-world performance changes with loop temperatures through the season, and the published ratings include only a small allowance for pumping — the full energy of the loop circulator is extra. A well-designed loop with efficient circulators keeps that penalty small.
Frequently asked questions
What are the efficiency ratings of the Tetco TWV060?
In its closed-loop water-to-water configuration it is rated at an EER of 21.9 for cooling and a COP of 3.5 for heating. Closed-loop ratings use 77 °F entering fluid for cooling and 32 °F for heating.
Can the Tetco TWV060 be used with both open and closed loops?
This listing covers its closed-loop rating. Manufacturers often certify the same water-source unit separately for closed-loop and open-loop use, each with its own EER and COP, so check the Tetco literature (or other listings for model TWV060) for the configuration you plan to install.
How much does it cost to heat with the Tetco TWV060?
At a COP of 3.5 it needs about 84 kWh per million Btu of heat, or about $14.23 at $0.17/kWh. A home needing 50 million Btu a year would spend roughly $712, before loop-pump energy and any auxiliary heat.
What refrigerant does the Tetco TWV060 use?
The ENERGY STAR record lists R-410A.
Does the Tetco TWV060 heat with forced air or hot water?
Hot water. It is a closed-loop water-to-water unit that heats water for radiant floors, fan coils, low-temperature radiators or a buffer tank; it does not blow air on its own.
Is the Tetco TWV060 ENERGY STAR certified?
Yes. It appears on the ENERGY STAR certified geothermal heat pump list, with a certification date of August 2023, and it is also designated ENERGY STAR Most Efficient.
Sources and disclaimer
Specifications on this page come from the ENERGY STAR certified geothermal heat pumps dataset published by the U.S. Environmental Protection Agency (record certified August 9, 2023), retrieved October 7, 2026.
The setup, operating, maintenance and troubleshooting guidance is written by ManualHarbor's editors for this specific product type and configuration. It is an independent guide — not a reproduction of the manufacturer's manual — and ManualHarbor is not affiliated with Tetco. Always follow the safety instructions, installation requirements and warranty terms supplied with your unit, and contact Tetco or an authorized service provider for warranty repairs and replacement parts.
Running-cost figures use assumed U.S. average utility prices and are estimates for comparison only. See our editorial methodology for details.
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